Combustion exhaust flue gases discharged from coal burning facilities and heavy oil burning facilities such as boilers contain sulfur oxides (Sox). As sulfur oxides pollute the atmosphere and adversely affect the global environment, such facilities are broadly required to install a flue gas desulfurization system for absorbing and removing sulfur oxides from the combustion exhaust flue gas they discharge.
Flue gas desulfurization systems designed to blow sulfur oxides-containing flue gas into an absorbent-containing absorber solution and cause it to bubble for the purpose of desulfurization are being widely adopted because such systems provide a high gas-liquid contact effect and can achieve a high desulfurization efficiency and also a high dust removing efficiency.
In a jet bubbling reactor type flue gas desulfurization system, flue gas is blown into the absorber solution stored in an absorber solution chamber. Then, the sulfur oxides contained in the flue gas are absorbed by the absorber solution and subsequently the desulfurized flue gas is led into a desulfurized flue gas inflow chamber arranged above the absorber solution chamber. In the desulfurized flue gas inflow chamber, liquid droplets and other objects contained in the flue gas are removed before the flue gas is finally discharged from the system. It is known that, in the desulfurized flue gas inflow chamber, solid components (mainly gypsum) contained in the liquid droplets that accompany the flue gas led into the desulfurized flue gas inflow chamber settle there and accumulate on the bottom surface of the desulfurized gas inflow chamber.
Known techniques for washing out the accumulated solid components include, for example, a method of supplying cleansing solution into the desulfurized flue gas inflow chamber and flushing down the solid components through a down comer along with the cleansing solution. However, as the cleansing solution is discharged into the absorber solution chamber, the surface level of the absorber solution fluctuates as a function of the flow rate of the cleansing solution that comes flowing down through the down comer. Then, as a result, the desulfurization performance can become instable in some instances.
In view of the above-identified problem, PTL 1 describes a flue gas desulfurization system in which cleansing solution is fed into a desulfurized flue gas inflow chamber in order to cleanse and remove the accumulated solid components and then the cleansing solution is discharged from the desulfurized flue gas inflow chamber to the outside of the system along with the solid components by way of a cleansing solution discharge pipe. According to PTL 1, the flue gas desulfurization system described in it discharges the cleansing solution from the desulfurized flue gas inflow chamber to the outside of the flue gas desulfurization system so that it can eliminate any external turbulence that can fluctuate the surface level of the absorber solution in the absorber solution chamber and thereby stabilize the desulfurization performance of the system.